PLASTER OF PARIS Recipe

Plaster of Paris is a Calcium sulfate semi-hydrate (CaSO4, 1/2 H2O) derived from Gypsum, a calcium sulfate di-hydrate (CaSO4, 2H2O), by firing this mineral at relatively low temperature and thus reducing it to powder.

CaSO4,  2H2O  + HEAT -------> CaSO4, 1/2 H2O  + 1.5 H2O

In 1700’s, Paris was already the “Capital of plaster” since all the walls of wooden houses were covered with plaster, as a protection against fire. The King of France enforced rule after the big fire in England 1666.

Large Gypsum deposits near Paris ► Mined ► Manufacture of Plaster of Paris

Items Needed

(Apparatus) to make plaster of paris with glue

Properties of Plaster Of Paris

• It is fine hygroscopic white powder
• Its melting point is 1630C
• Its density is 2.63 g/cm3
• It sets quickly on mixing with water giving out heat
• Expands slightly on setting

USES of Plaster of Paris

• Because of its property of slight expansion on setting, it is used for filling cracks and holes in plaster
• It is also used for filling cracks and knots in wooden surface before painting polishing
• Plaster of Paris is used in making surgical bandages where movable parts of the body are to be held rigidly in place
• It is used in chalk
• As plaster of Paris has high melting point, it is used for plastering the walls of wooden houses, such as a protection against fire
• It is used for making models and statues

• CBR Graphs
• Significance of CBR Concrete tests
• Bitumen tests
• Civil Lab Tests
• Transportation Engineering
• Road Structure Cross Section Raised Pavement Markers
• Highway Maintenance
• Bearing Capacity